I voted D but, in the real world I think it depends upon the size of the woman.
My wife is 5'7" and she had D tits that looked big on her because she was only 34" round the rib cage. When she became pregnant they grew to E and in the first month after our son was born they went to F and then G, which was not only ridiculously big but very expensive in bras. After she stopped breastfeeding they shrank down to DD and stayed at that size. She later lost them both to breast cancer so they're just a memory now, but we still have some nice photos to remind us.